Rachael was born October 4, 1979, in Minneapolis, Minnesota, and graduated from high school in Spring 1998. Rachael got her first acting role when she was around seven in a non-speaking part in a public service announcement encouraging adults to become foster parents. Rachael began doing modeling advertisements at the age of ten, and probably her best known for doing spots for Target and Milkbone. She also appeared in a now-famous anti-drug TV spot in which, armed with a frying pan, she bashed her way through a kitchen to show the disastrous effects of heroin.

On reaching L.A., Cook bypassed the wannabe stage and nailed her first audition (for the part of a budding entrepreneur in Baby-Sitters Club, The (1995)). She returned to theaters three months later in the Jonathan Taylor Thomas vehicle Tom and Huck (1995), then filled her calendar with appearances in independent and made-for-TV movies. She divided her time between Minneapolis and Tinseltown, shuttling from school events to movie shoots with her mother in tow. Cook's starlet status crystallized in 1999, when she starred opposite Freddie Prinze Jr. in the Pygmalion retelling She's All That (1999). She won acclaim also as Becky Thatcher in Tom and Huck, starring opposite Jonathan Taylor Thomas ("Home Improvement"). However before catching the eye of the nation, she was a model for print ads for about four years. Her spots in the Target Stores ad and on the cover of a Milkbone dog biscuit box are probably her best known ones.

Rachael has gone on to make 11 movies in just 3 years, including Carpool, Living Out Loud and Strike. Other films that she has done recently include Hi-Line, an independent film, The Bumblebee Flies Anyway, a teen drama set in a hospital that also stars Elijah Wood, and The Naked Man, a comedy about sumo wrestling written by Ethan Coen. She signed for a handful of plum follow-up roles, including a troubled adolescent in Sylvester Stallone's Get Carter (2000), a frontier gal in Texas Rangers (2001), and the caterwauling lead in the live-action version of Josie and the Pussycats (2001). Rachael is passionate about art, especially drawing, and she would like to eventually try screen writing and has co-produce an independent film entitled "Tangled". Rachael enjoys reading, writing, tennis, roller blading, and shopping for clothes.